| 日時: |
2008-04-28 14:00 - 15:00 |
| 場所: |
研究本館２階２２０室 |
| 会議名: |
Multi-Particle Processes in the Standard Model with HELAC |
| 連絡先: |
津田 |
| 講演者: |
Dr. Malgorzata Worek (Karlsruhe University, Germany) |
| 講演言語: |
英語 |
| アブストラクト: |
One of the most striking features of LHC final states will be the large number of events with several hard jets. Final states with 6 jets from ttbar decays will have a rate of almost 1Hz, with 10-100 times more coming from prompt QCD processes. The immense amount of available phase space, and the large acceptance of the detectors will lead to production and identification of final states with 10 or more jets. These events will hide or strongly modify all possible signals of new physics. Being able to predict their features is therefore essential. However, the estimation of multi-jet production cross sections and their characteristic distributions is a difficult task. Perturbation theory based on Feynman graphs runs into computational problems, since the number of graphs contributing to the amplitude grows as n!. Fortunately, over the last few years recursive algorithms based on Dyson-Schwinger equations have been developed in order to overcome the computational obstacles. The amplitude calculated using Dyson-Schwinger recursive equations results in a computational cost growing asymptotically as 3^n, where n is the number of particles involved in the process. In this new approach, the off-shell subamplitudes are introduced which are combinations of parts of Feynman graphs. For those subamplitudes a recursion relation has been obtained which enables to express an n-particle amplitude in terms of all subamplitudes, starting from 1-, 2-, ... up to (n-1) particles. I will present a Monte Carlo library HELAC which is based on Dyson-Schwinger recursive equations and can be used to efficiently obtain helicity amplitudes and total cross sections for arbitrary multiparticle processes in the Standard Model in leptonic and hadronic collisions.
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